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Study Of Polymer Composites Containing Nano- And Micro-particles For Materials Engineering Applications

Fiaz, Ahssad (2018) Study Of Polymer Composites Containing Nano- And Micro-particles For Materials Engineering Applications. PhD thesis, University of Sheffield.

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Abstract

The research conducted in this report is broad; however, it demonstrates innovative approaches for several potential applications. The projects advocate the use of composite scaffolds to enhance or improve the roles of standard polymer-based materials. Two techniques have been utilised to create the structures, poly-high internal phase emulsions, templated using two immiscible liquids, and the continuous phase containing the monomer material. Also, hydrogel synthesis, a hydrophilic monomer cured to form a highly swellable polymeric gel. The three subject areas are polymeric hydrogels – as potential sensors; microcarriers for bone and tissue engineering, and poly-high internal phase emulsions (poly-HIPEs) as thermal insulators; all three are briefly outlined below in chronological order of their chapter allocation: The production of polymeric sensors is the application considered in the following chapter using the environmentally sensitive polymer – poly-isopropyl acrylamide. Initially started using the poly-HIPE route, but the attention was focused on hydrogels as a more suitable alternative. Due to the improved mechanical nature and ability to retain structural integrity in water, the properties were enhanced using magnetically responsive nano- and micro-particles. The project utilises ferrogels are hydrogels loaded with magnetite that were synthesised via a co-precipitation and solvothermal route, creating particle sizes of 1 – 10 nm and around 250 nm, respectively. Additionally, the use of Maxwell-inductance Bridge demonstrates a low, but detectable response for in-situ samples. Although results for the Microparticle containing gels are unclear, they possess significant volume transition responses compared to in situ ferrogels; and with some modification of the inductance bridge, there is potential for the transition of micro-ferrogels to be detectable with the chosen sensing method. Microcarriers are highly porous materials that provide a surface suitable for cellular adhesion. In this case, emulsion templating was utilised to create porous beads with embedded carbonyl-iron particles to provide a magnetic response. By applying an external magnetic field, a novel method is used to create fluid shear stress in order to encourage osteogenic differentiation. Common osteo-indicators such as alkaline phosphatase activity, collagen and calcium were used as a measure for an osteogenic response. In the last section, a case for Poly-HIPEs as thermal insulation materials is proposed. Due to their controllable nature, they have characteristics similar to those found in insulation materials, small pores, a highly porous and hydrophobic structure are key factors in quality insulators. Porosity was controlled by increasing the volume of water, which formed the internal phase; samples with 60% to 90% were manufactured. The conductivity of the material was similar to conventional insulators; however, they were less insulating with increasing porosity. Addition of wood fibre improved the insulation properties of the 90% porous sample but had the opposite effect on the sample with low porosity.

Item Type: Thesis (PhD)
Academic Units: The University of Sheffield > Faculty of Engineering (Sheffield) > Materials Science and Engineering (Sheffield)
Identification Number/EthosID: uk.bl.ethos.784680
Depositing User: Mr Ahssad Fiaz
Date Deposited: 09 Sep 2019 08:26
Last Modified: 25 Sep 2019 20:08
URI: http://etheses.whiterose.ac.uk/id/eprint/23341

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